There are many instances in which rapid field evaluation of heavy mineral content of various ground samples is desired. While various different forms of vibratory heavy sample concentrators heretofore have been designed, most of these previously known devices have included vibratory screen structures designed to be oscillated back and forth between their limits of movement through relatively reversed but otherwise substantially identical cycles of operation. However, it has been found that variances in the speed of movement occurring during the relatively reversed cycles of operation of a vibratory screen may enable more effective concentration of the heavy components of a soil sample. Accordingly, a need exists for a vibratory sample concentrator which may be effectively driven through its reverse cycles of movement at varying speeds in order to allow the most effective concentration of heavier components.
Examples of vibratory heavy soil component concentrators and separators including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 388,464, 430,335, 1,230,477, 2,663,923, 2,709,521, 3,109,808 and 3,313,415.